Cam grinding machine



c. w. LANG 2,334,938

CAM GRINDING MACHINE Nov. 23, 1943.

Filed Ma rch 29, 1945 2 Sheets-Sheet 1 INVENTOR. ARLES WLmva 147' TORNEYNov; 23, 1943. v c. w. LANG 2,334,938

CAM GRINDING MACHINE Filed March 29, 1945 2 Sheets-Sheet 2 INVENTORj VCHARLEJ W Ln/vs ATTOQNEY Patented Nov. 23, 1943 CAM GRINDING MACHINECharles W. Lang, San Francisco, Calif., assignor to Enterprise Engine &Foundry Company, San Francisco, Calif., a corporation of CaliforniaApplication March 29, 1943, Serial No. 480,923

7 Claims.

This invention relates to machines for making duplicate cams by thegrinding process from cast or roughly formed blanks, under the controlof a master or template cam, on the general principle of a duplicatinglathe, and the object of the invention is to provide improvements insuch a machine whereby it takes the form of a very compact machineadapted for grinding rim cams.

Other objects and features of the machine will appear in the followingdescription and accompanying drawings.

In the drawings:

Fig. 1 is a perspective view of my improved cam grinding machine withmaster cam and the duplicate cam being ground, shown in place.

Fig. 2 is a plan view of the machine with the work shaft driving gearassemblage omitted.

Fig. 3 is a vertical cross section of the machine taken along the line33 of Fig. 2.

Fig. 4 is a vertical end elevation of the machine taken from theright-hand end of Fig. 2.

Fig. 5 is a perspective view showing the grinding wheel dresser inposition.

Briefly described the machine comprises two spaced parallel shafts Iand. 2, rotatably mounted on a supporting base 3, one shaft carrying themaster or template cam 4 at one end and the blank or cam 5 to be ground,at the other end. Shaft l is the grinding wheel motor shaft and is alsooscillatingly mounted to the base 3 as by brackets 6 to a pivot shaft 1so as to be swingable toward or away from shaft 2, and carries agrinding or abrasive wheel 8 at its outer end in confronting rimrelation with the cam 5 to be ground. A counterweight or springconstantly urges shaft l and its grinding wheel to swing toward shaft 2,while means is provided for controlling and limiting the approach of thegrinding wheel 8 to cam 5 to grind it to the shape of template or mastercam 4 through the action of a limiting roller or wheel 9 which bearsupon the finished surface of the master cam 4.

Shaft I is really the extended shaft of the armature of an electricmotor IE which revolves it and the grinding wheel 8 in direction of thearrow shown on the wheel, while the cam 5 to be ground is slowlyrevolved in the same direction by a motor ll through the intermediary ofsuitable worm gear reduction drive in housing 2.

While it was stated above that shaft l was oscillatingly mounted onpivot shaft 1, it is really the motor IU which is mounted on brackets 5and these are rigidly secured to pivot shaft I, but of course the motorand its shaft 1 swing as a unit on the arc X (see Fig. 1) and they areresiliently urged to swing to the left (Fig. 4) so as to keep thegrinding wheel in contact with the work cam 5, by means of acounterweight i 3 which is loosely housed Within an upward extension 3'of the base 3 and freely slidable up and down on a pair of spaced fixedguide rods 24. This weight engages a laterally extending lever or crankarm 15 which is rigidly secured at one end to the pivot shaft l andprojects through an opening E6 in the side of the elevated part 3' ofthe base and into a hole ll in the weight where the end of it isimpinged by a rounded end set screw |8 screwed through the upper portionof the weight IS. A weight is used as its pressure is uniform and notsubject to the vibratory action of a spring.

The grinding wheel is of wider face than the rim cam to be ground and istrimmed to an absolutely true face parallel to shafts I and 2, and itshould be about the same diameter as idler .wheel 9, for if it could bekept precisely the same diameter as wheel 9, and wheel 9 were alsomounted on an extension of the motor shaft it would stop grinding whenthe new'cam 5 became the exact size and shape of master cam 4.

However, as the grinding wheel cannot be maintained at a definiteconstant diameter, a hand screw or feed adjustment is provided to varythe oscillatory relation of idler wheel 9 to the axis of the motor shaftl, and to carry this out idler wheel 9 is mounted on a separate shortaxle l9 projecting from the upper end 20 of a bracket 20 which is freelypivoted about pivot shaft '1 so that While it swings in the same are asdoes the motor 10 and grinding wheel 8 it is independent thereof, butidler wheel 9 is always kept pushed into rolling contact with the mastercam 4 by means of a hand-screw 2| threaded through a lug 22 fixedlyprojecting from the end of the motor frame iii, and the inner end ofwhich screw bears against the outer edge of the upper end 23 of bracket20 so that by turning the screw 2! by means of its handle 23 the motorH1 and its grinding wheel may be forced to back off or away from the cam5 being ground so as to be free of contact therewith, or by turning thescrew in the opposite direction the Wheel may be permitted (under theaction of the coun terweight H) to gradually approach the work and beginto grind it.

By this hand screw control the cam 5 may be brought down to the exactsize and shape of the master cam, and by having the screw motion limitedthe grinding could proceed no further,

extended through the base to the motors.

but as stated, since the grinding wheel will gradually become smaller,the screw travel is made sufficient to permit grinding the work tosome.- what smaller diameter than desired, and it is therefore carefullymeasured for correct final diameter and the grinding wheel backed offwith the hand screw 2! when exactly right in size.

While the counterweight always urges the motor II] and its grindingwheel 8 toward the work, and through hand screw 2! also urges the idlerwheel 9 against the master cam 4, still to prevent any possible backlash a compression spring 24 is positioned opposite the hand screw 2!reacting between bracket 29 and a lug 25 projecting from the motor frame[0.

The work shaft 2 is as stated, driven by a sep arate electric motor llthrough worm gearing 01 other reduction gearing in gear box l2 so as torevolve slowly as the grinding wheel revolves at high speed against thwork, however, since the idler wheel 9 is pressed against the master camwith some force it might urge shaft 2 to move ahead at such times as itwas riding up to a high part of the master cam. This would be possibledue to some backlash in the reduction gearing, and to prevent this agentle tho constant brake pressure or frictional resistance is appliedto the work shaft 2 by means of a brake strap 26 passing over a brakewheel or disk 2! secured to shaft 2 and provided with suitableadjustments to provide the required resistance.

Brake wheel 2! is provided with a finished hub 28 secured to shaft 2 andover which the master cam 4 fits and is held in place by a collar 29 andnut 30 on a reduced portion of shaft 2, while at the extreme end of theshaft is any desired type of detachable coupling 3| for connecting theshaft to the reduction gear output shaft connecting member 32.

Means is also provided to insure correct angular relation of the mastercam and the cam being ground and prevent slippage from this position.

In the drawings this is carried out by a pair of driving pins 33extending from the side of the brake wheel or disk 21 which enter a pairof corresponding holes drilled through the master cam. A similarconstruction is used at the opposite end of shaft 2 where the cam 5being ground fits over a. hub 35 secured to the shaft and is angularlylocated as by one or more feather keys 36 over which it slides.

As the grinding wheel does not move axially with respect to the cambeing ground as with many grinders, the wide face of the wheel must bekept true, and to do this quickly, just before sliding a new cam blankin place on hub 35 the special wheel dresser shown in Fig. 5 is placedon the hub 35 and moved back and forth longitudinally thereon while thegrinding wheel is running to take off any slight irregularities. Theamount of the cut may be accurately controlled by the hand screw 23. Ofcourse the work shaft .2 will be stopped during this operation whichrequires but a few moments of time. The special dressing tool comprisesa base portion 31 concavely curved to fit over hub 35 and provided witha keyway to slidably fit one of the feather keys 36. The cutting point39 may be a diamond adjustably secured in a lug Mi provided on the baseportion 31. A handle M facilitates manipulating the device.

Separate switches for the two motors are provided on the base 3 as shownat 52 and 43 in Fig. 1, and with the wiring (not shown) suitably Alsothe usual protective hood is provided over the grinding wheel as is wellunderstood, but omitted from the drawings to more clearly show therelation of the parts.

From the above combined description and operation of the machine, itsmode of operation and advantages will be easily understood by anyoneskilled in the art, and while I show the grinding shaft as movable andthe work shaft in fixed rotative position, this relation may be reversedwhile still maintaining advantages of the invention and my claims areintended to cover any such equivalents.

I claim:

1. In a rim-cam grinding machine, a rotatably mounted work shaft, meanson said work shaft supporting a rim-cam blank to be ground to form, andmeans also supporting a master rim-cam on said work shaft in fixedangular relation to said cam blank, means for driving said work shaft, agrinding shaft provided with a grinding wheel in confronting rimrelation to said cam blank, means mounting said grinding shaft forrotation and moving bodily toward and from said work shaft, an idlerwheel arranged to roll against the rim of the master cam as the same isrevolved with the work shaft, bearing means rotatably supporting saididler wheel and mounted for movement back and forth as the wheel ismoved by the master cam, a driving motor on the grinding shaft, a handscrew arranged to react between the motor frame and said bearing meanstending to force the idler wheel toward the master cam and thereby tocontrol the separation of the grinding shaft from the work shaft, andmeans resiliently urging the two shafts toward one another.

2. In a rim-cam grinding machine, a hollow base plate, a work shaft anda grinding shaft rotatably mounted in parallel spaced relation abovesaid base, the mounting of the grinding shaft including brackets securedto a pivot shaft in turn rotatably mounted upon said base whereby thegrinding shaft may swing bodily toward and from said work shaft, meansmounting a rimcam blank to be ground on one end of the work shaft, agrinding wheel mounted on the grinding shaft in confronting rim relationto the cam blank, an electric motor on said grinding shaft, a leversecured to and projecting laterally from said pivot shaft, acounterweight within said hollow base plate suspended from said leverurging said grinding shaft with its motor and grinding wheel to swing indirection of said work shaft,

a master rim-cam secured to said work shaft to which form the cam blankis to be ground, a bracket loosely pivoted to said pivot shaft, an idlerwheel carried by the bracket arranged to roll against said master cam asit is revolved with the work shaft, and screw means extending betweensaid grinding shaft and said bracket tending to force the idler towardsaid master rim-cam and back away said grinding shaft, for varying theeffective distance between the grinding shaft and the work shaft,

3. In the construction as set out in claim 2 spring means reactingbetween said grinding shaft and said bracket urging it toward said screwmeans.

4. In the construction as set out in claim 2 a separate electric motormounted on said base plate provided with speed reduction gearingdetachably connected to drive said work shaft, and a brake active onsaid work shaft to hold same against turning in advance of its motordrive.

5. In the construction as set out in claim 2 a separate electric motormounted on said base plate provided with speed reduction gearingdetachably connected to drive said work shaft, and a brake active onsaid work shaft to hold same against turning in advance of its motordrive, and separate control switches for the two motors mounted on saidbase plate.

6. In the construction as set out in claim 2 said counterweight beingslotted for reception of said lever, and movable up and down on guidingpins secured to the base plate.

7. In a structure as set out in claim 1 the means on the work shaftsupporting a rim-cam blank to be ground to form, comprising a hub uponwhich the rim-cam blank is slidably secured and removable, and agrinding wheel dresser formed with a base adapted to slidably fit uponsaid hub When the cam blank is removed, said dresser adapted formanually moving back and forth along said hub when the Work shaft isstill, and a grinding wheel dressing cutter mounted on said base inconfronting relation to the rim of said grinding Wheel.

CHAS. W. LANG.

